I have a Garmin 810 and an iPhone 5 with Cyclemeter. Last year, I bought the bluetooth sensors from wahoo fitness and went exclusively with Cyclemeter. I like it better for the better display, the increased functionality and it seems to be just as accurate as the Garmin. Since I have to carry a phone anyhow, it's just one less thing I need to have with me. Since I use the quadlockcase mounting set up on the stem, then it's one less thing in my jersey pockets. What's not to like?

Cyclemeter seems to be quite repeatable. If I ride the same route, I get the same altitude gain and the same distance (varies a tiny bit, but I presume I do too). So I'm pretty happy with it.

J.